1. Field of the Invention
This invention relates to an additive dispensing system which may be used for dispensing additive fluid into a storage tank while the storage tank is being filled with fluid. Specifically the invention relates to an additive dispensing system that requires no electrical power to pump additive into a tank. The invention finds application for fuel additive systems for fuel tanks of trucks and any equipment that has a fuel tank to which mileage enhancing additives can be added. The invention also find application for adding corrosive additives such as chlorine to tanks so as to avoid corrosion to pumps, etc.
2. Background Art
Additive dispensing systems usually require external electrical power for operation. The power is used to energize various types of pumps, meters, level sensors and controls that cause the system to add an additive to a tank in proportion to the fluid, e.g., fuel, being added to the reservoir tank.
FIG. 1 illustrates such a prior art system. Proportionality is achieved by metering both the fluid (10) being loaded into the reservoir (12) and the fluid (20) being dispensed by an injector. Electronic signals from both meters (14, 24) are monitored and tabulated by a PLC (programmable logic controller) (30) which, in conjunction with pre-programmed formulas, calculate pump performance requirements and send electrical power to a variable speed pump (32) by means of a compound loop controller. The speed of the delivery pump (32) is determined by pulses received from both additive and product meters (14, 24) which are calculated and processed by the on-board PLC (30).
Such systems are very complex, are in most cases fragile, and are subject to stray electrical interference typically found on highway trucks. In many cases, vehicle manufacturers will void their warranties if foreign equipment is installed that could pose a threat to the integrity of the vehicle's on-board systems. Constant vibration, variable temperatures, harsh environments and inconsistent operator interfaces can make such systems undependable which significantly diminishes fuel economy and performance of the vehicle.
Another example of prior art, is a system that measures fluid volume either by means of weight or some version of a level indicator (16) of fluid (10) in the tank (12) to be additized. FIG. 2 illustrates such a prior art system. After the tank (12) is filled, and the volume measured, a calculated volume of additive (20) is then dispensed by means of a processor (30) and variable speed pump (32). Such systems are subject to failure due to the delicate nature of tank level measuring devices (16) when subjected to constant vibration found on various commercial vehicles. Like the meter paced system of FIG. 1, these systems are expensive and require interface with vehicle systems.
Fixed rate delivery systems such as described in FIG. 3, which may be powered by air or electricity, depend on operator judgment in order to assure proper dosage when fuel is added to a fuel tank (12), since the systems operate at a fixed delivery rate and must be activated manually by the operator fueling the vehicle. Since fueling rates of flow vary significantly from station to station, it is impossible for this type of system to meter the additive proportionately.
In general, previous and current devices available to the trucking industry is often too expensive relative to the fuel savings realized by additive injection and in addition, require high levels of maintenance with unacceptable levels of dependability. All conventional additive systems employ various pumps which in most cases depend on the integrity of valves, seals, diaphragms, piston seals and other dynamic seals for efficient operation requiring high levels of maintenance and incidence of failure or out-of-specification performance.